Read This Before You Decide to Buy Your Solar Panels
Some renewable energy experts would recommend steering completely clear of used solar panels. For homeowners who lack technical skills and want to eliminate risk, the best practice for saving money is to buy unused surplus or discontinued panels being liquidated by resellers with excess inventory. Buying used solar panels does require that you know what you’re looking for in terms of what issues are red flags versus issues that are actually less serious that they might seem at first glance. They main reason that used solar panels might be worth a little risk and inconvenience is that you might very well wind up with a spectacular deal. An astute shopper can buy a solar panel for $1 per watt.
The most important piece of advice is to buy local. Online marketplaces like eBay, or even vendors who sell used solar panels exclusively, have no way of allowing you to test the output of the panel under consideration, nor can you inspect is closely prior to paying for shipping. Look to flea markets, recycling centers and farm auctions where you can examine and test the panel in person.
Speaking of testing, always bring a multimeter with you whenever you’re shopping for a panel. You don’t need a sophisticated model–just something that measures voltage and amperage; so the cost should under $20. The object is to see how closely the panel’s output matches its stated rating. If the panel has had years of use, don’t expect a close match. Solar panel manufacturers usually state a life expectancy of around 30 years for a typical panel, but its efficiency will still degrade in the interim. If a used panel is within 50% or more of its specification, it’s a viable purchase as long as the price is right. Even inefficient panels still provide all of the core advantages of solar energy. Keep in mind that you’ll probably need to purchase several panels and run them together in series. What’s important is whether or not you can purchase enough total power to supply your house’s energy needs for less money that you would spend for new panels. You can still can almost all the advantages of solar energy with suboptimal panels.
When you’re looking at older panels, don’t worry about browning. All photovoltaic panels brown over time, but the coloration doesn’t affect their performance. On the other hand, do be concerned about defects like loose wiring, cracks in the glass or condensation trapped underneath. If you see these, they might not be worth testing with the multimeter, since the conductivity will be reduced (or terminated if the circuit is broken). Whether or not these defects are dealbreakers is a judgement call. You can solder loose connections if you have soldering skills, or if you don’t, you can use a conductive epoxy infused with silver (e.g. SilverPrint). There are almost always options for restoring solar panels. The trick is to know when you’re buying a solar panel at a low enough price to still come out ahead after any and all repairs.